This invention relates to an image forming apparatus that can typically find applications in a quadruple tandem color electrophotographic apparatus.
A quadruple tandem color electrophotographic apparatus comprises four processing units arrange at certain intervals. The four processing units are provided with respective photosensitive drums. Around each of the photosensitive drums, there are arranged an electric charger for electrically charging the surface of the photosensitive drum to a predetermined electric potential, an exposure device for forming an electrostatic latent image on the surface of the photosensitive drum, a development device for developing the electrostatic latent image, a transfer charger for transferring the toner image onto a sheet of printing paper and a cleaner for removing the toner remaining on the photosensitive drum. The development device of the processing units are adapted to feed toners of different colors.
The electrostatic latent image formed on each of the photosensitive drums of the processing units is developed to produce a toner image as developing solution is fed from the development device. The toner images formed on the photosensitive drums are then sequentially transferred onto the sheet of paper being transported in an overlapping fashion to produce a color picture.
The developing solution fed from the development device typically comprises two components, a non-magnetic toner and a magnetic carrier that are mixed with each other. The service life of the developing solution terminates when the density of the formed image falls and/or when the image becomes remarkably foggy. Normally, it is considered that the apparatus needs servicing when the service life of the developing solution ends and a service person is called in to check the apparatus and manually replace the developing solution.
However, it is not efficient that the developing solution is manually replaced by a service person.
Therefore, in recent years, some cartridges containing toner and adapted to feed the development device with toner are made to also contain a liquid carrier in a mixed state so that both the carrier and the toner may be supplied periodically to the apparatus. When supplying the carrier, the developing solution remaining in the development device is removed by an amount corresponding to the amount of the carrier that is newly supplied. With this arrangement, the developing solution in the development device is prevented from being degraded and the manual replacement of developing solution does not take longer than necessary.
However, conventionally, the use of a specifically designed developing solution removing mechanism is required, which makes the supply of developing solution still costly and the image forming apparatus bulky.
In view of the above identified circumstances, it is therefore the object of the present invention to provide an image forming apparatus that is adapted to be supplied with developing solution without requiring a specific developing solution removing mechanism.
According to the invention, the above object is achieved by providing an image forming apparatus comprising:
a plurality of image carriers arranged in parallel at predetermined intervals;
a plurality of image forming means for forming respective images on the plurality of image carriers;
a plurality of development means for feeding 2-component type developing solution containing toner of respective different colors and carrier to the respective electrostatic latent images formed on the plurality of image forming means and developing the electrostatic latent images;
a transfer device for moving an image receiving member to the image carriers and transferring the developed images on the image carriers sequentially onto the image receiving member in an overlapping fashion to produce a color image;
a plurality of cleaners for removing the developing solution remaining on the respective image carriers after the transfer of the developed images;
collection mechanisms arranged respectively in the cleaners and adapted to transport and collect the removed developing solution;
a supply device for supplying the development devices with 2-component developing solution containing toner and carrier; and
a discharge port arranged at least at one of the development devices and adapted to discharge part of the 2-component developing solution already contained in the apparatus at the time of supplying developing solution;
the developing solution discharged from the discharge port of the development device being let to fall and collected in the cleaner located at an upstream position of the development device along the moving direction of the image receiving member so as to make the developing solution in the cleaner to be collected and removed by the collection mechanism.
In another aspect of the invention, there is also provided an image forming apparatus comprising:
a plurality of image carriers arranged in parallel at predetermined intervals;
a plurality of image forming means for forming respective images on the plurality of image carriers;
a plurality of development means for feeding 2-component type developing solution containing toner of respective different colors and carrier to the respective electrostatic latent images formed on the plurality of image forming means and developing the electrostatic latent images;
a transfer device for moving an image receiving member to the image carriers and transferring the developed images on the image carriers sequentially onto the image receiving member in an overlapping fashion to produce a color image;
a plurality of cleaners for removing the developing solution remaining on the respective image carriers after the transfer of the developed images;
collection mechanisms arranged in the cleaner and adapted to transport and collect the removed developing solution;
a supply device for supplying the development means with 2-component developing solution containing toner and carrier; and
a discharge port arranged at least at one of the development means and adapted to discharge part of the 2-component developing solution already contained in the apparatus at the time of supplying developing solution;
the developing solution discharged from the discharge port of the development device being let to fall and collected in the cleaner located at an upstream position of the development device along the moving direction of the image receiving member so as to make the developing solution in the cleaner to be collected and removed by the collection mechanism.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.